The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to computer interface devices that allow the user to provide input to computer systems and allow computer systems to provide haptic feedback to the user.
A user can interact with an environment displayed by a computer to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, using a computer aided design system, operating a graphical user interface (GUI), etc. Common human-computer interface devices used for such interaction include a mouse, joystick, trackball, steering wheel, stylus, tablet, pressure-sensitive sphere, or the like, that is connected to the computer system controlling the displayed environment. Typically, the computer updates the environment in response to the user's manipulation of a physical manipulandum such as a joystick handle or mouse, and provides visual and audio feedback to the user utilizing the display screen and audio speakers. The computer senses the user's manipulation of the user object through sensors provided on the interface device that send locative signals to the computer. For example, the computer displays a cursor or other graphical object in a graphical environment, where the location of the cursor is responsive to the motion of the user object.
In some interface devices, force feedback or tactile feedback is also provided to the user, more generally known herein as “haptic feedback.” These types of interface devices can provide physical sensations which are felt by the user manipulating a user manipulandum of the interface device. One or more motors or other actuators are coupled to the joystick, mouse, or other device and are connected to the controlling computer system. The computer system controls forces on the joystick or mouse in conjunction and coordinated with displayed events and interactions by sending control signals or commands to the actuators. The computer system can thus convey physical force sensations to the user in conjunction with other supplied feedback as the user is grasping or contacting the interface device or manipulatable object of the interface device.
Low-cost haptic devices tend to provide tactile feedback, in which forces are transmitted to a housing or portion thereof and felt by the user, rather than kinesthetic feedback, in which forces are output directly in the degrees of freedom of motion of the interface device. For example, many currently-available gamepad controllers include a spinning motor with an eccentric mass, which outputs vibrations to the housing of the controller in coordination with events occurring in a game. In some haptic mouse devices, particular areas on the housing of the mouse can be vibrated in accordance with interaction of a controlled cursor with other graphical objects, which the user feels by touching those housing areas. These tactile devices are typically less sophisticated than kinesthetic devices and therefore are much less expensive to produce.
In addition, haptic feedback devices, such as mice in particular, can be made less costly to produce by making them relative positioning devices rather than absolute positioning devices. For example, a standard computer mouse is a relative device which provides only a change in mouse position to the host computer to control a cursor. This allows the mouse to be freely lifted from the reference surface and requires simpler encoder sensors or the like. Absolute devices, in contrast, are often constrained to an absolute sensing range and may require more expensive sensors in some embodiments.
One problem with such inexpensive haptic controllers is their limited ability to convey certain types of force sensations to the user. For example, many tactile mice are incapable of providing spring and damper sensations in the degrees of freedom of the mouse. These types of devices tend to be limited in producing other spatially-based force sensations as well. Textures, for example, are force sensations which are based on the position of a controlled cursor in a graphical environment. If the cursor is moved over a textured area, the user of the haptic device should feel forces that are output in coordination with the cursor moving over each texture bump where it is located in the graphical environment. Texture sensations are often effectively produced by imparting a damping or spring force on the mouse at regularly-spaced positions; tactile devices, however, cannot output damping or spring forces. Furthermore, it can be difficult to correlate forces with the location of texture features or other spatially-activated haptic sensations when a relative input device is used. Thus, some tactile devices of the prior art may instead provide a spatially-independent vibration to simulate a texture. Such vibrations are based on a time-based source waveform, not the motion or location of the device or the cursor, and thus tend to feel unrealistic to the user when a texture sensation is desired.